Propagation Characteristics of Ultrahigh-Δ Optical Waveguide on Silicon-on-Insulator Substrate

Abstract

A submicron rectangular waveguide with a relative refractive index difference Δ of 45% was fabricated on a silicon-on-insulator substrate, and its propagation characteristics were evaluated using the Fabry-Perot resonance method. The propagation loss was of the order of 10 cm -1 , and was dominated by light scattering at rough interfaces. However, a large modal effective index of more than 4.5 and a low bend loss of less than 1 dB at a 0.5-µm-radius bend were also observed. These results suggest the potential of an ultrasmall and high-density lightwave circuit, which accepts the relatively large propagation loss.